[johntbyrne]

I'd like to hear comments on linears and dust. I like the idea of a moving table due to having the strong gantry but I'm worried about dust on the ways if I use roller blade type setup. I know if I had the money I could use something like a Drylin bearing that wipes as it goes but I don't have this kind of money.

The X axis is probably the most critical followed by Y and then Z due to position. Correct? I think a roller blade setup for the Y isn't too bad since the bearings are at angles. I suppose you could put the bearings for the X in positions other than top center relative to the pipe to avoid the dust since it will flow off the pipe everywhere else other than top center.

I'd like to hear comments about your experiences and solutions. I can make seals for a moving table that will wipe the way but is this needed?

If there is already a discussion about this please forgive and point me to it. I failed to find it via search.

Thanks much
John

[wjbzone]

My Igus Drylin bearings only cost $68 for all three axis. (1" ID on X and 3/4" ID on the Y and Z).
Bill.

[johntbyrne]

What size machine do you have Bill? I'm looking at around 24" by 14" by maybe 3".

What type of drylin bearing are you using. I'm familiar with their linear slide type with metal rails, aka Igus but suspect you mean a bushing type of bearing. If so what about drag? I'm thinking I want to keep the machine as free as possible. Why? Heck if I know other than being a "purist" I suppose.

[trent2530]

I used roller skate bearings on gas pipe for my first machine, a router, and the sawdust had a sticky something in it and it would cling and build up on the top of the gas pipe. Now I use dualvee wheels and track. Haven't started using it yet, but should be better.

[johntbyrne]

Wow Bill,

Just checked out your web site. Beautiful machine you have there.

[johntbyrne]

Trent

This is what I'm afraid of. I think that without some sort of wipe dust and "junk" will build up on the pipe causing problems. What about a bushing type wipe just before the bearings? I've got to believe someone has solved this problem if it actually is a problem.

[yukonho]

Hi John.
My first machine is a moving gantry type and the rails (pipe) are partially covered by the table. They still get a fair amount of dust on them, but I wipe them every now and then and I have had no problems at all.
Machine number two is a moving table design. Have a look at the pictures here http://www.cnczone.com/forums/showth...s&pagenumber=7
I am going to cover the rails with a strip of plastic that will be attached to the box, not the table. It is tough to figure out what I am talking about with these pictures. I hope to do some more work on my machiine in the next couple of days, so I will post pics of what I mean.
co

[johntbyrne]

So does the plastic attached to the box fold or stretch or something as the table moves?

[yukonho]

No.
The rails are along the side of the table. The plastic will attach to the inside of the main box and sit above the rails and bearings. The top of the table will stick out over the plastic. The plastic is not attached to the table at all, and will not move.
I will post pictures as soon as I can, it is tough to describe.
co

[wjbzone]

John,
My cnc size is about 24 X 13 X 7. These are "bushing type" bearings.
Igus partnumbers:
WLI-1618-18
WLI-1214-13

I'm sure they have more drag than a roller type bearing, but with a ballscrew pushing it, I have no problems. (The Z axis will drop by itself if gravity is all that is acting on it).

I wipe the dust off the ballscrews and rails when it builds up and spray a light coat of WD40. MY 120 oz-in motors feed at about 15 ipm and rapid around 30 ipm.

To get the bushing to fit right, I had to hone out my bearing sleeves until the bearings pressed in and the slide felt good on the drill rod shaft. It was a little larger ID then the Igus specification called for.

Bill.

[johntbyrne]

I think I see Colin, looking forward to seeing more pics. Bill, how long have you been running (or how much time is on it). If the bushing doesn't wear and get "sloppy" this seems like the way to go for at least the X. Wonder if we could use roller blade bearings with a bushing in front of it to clear the way of dust? Kind of what I was thinking when I said make a seal.

[wjbzone]

I would just guess I've got around 200-300 hours run time. Everything is still tight. These bearings clear a set of paths (about 1/8" wide each) equal spaced around the guide where the bearing makes contact. Would you roller blade contact be wider then that?
Bill.

[johntbyrne]

Bill, I said that wrong, sorry. What I meant to say is make a bushing similar to Igus. I think I'd make it out of UHMW since I can get it for free. With that said, good point on the Igus. Their design will make lines of dust but this is also what allows it to have low drag.

BTW, why did you use the WL1 type bushing? There are others listed in the book that "suggest" they will work with same or better life but lower coefficient of friction.

Thanks for all the info
John

[wjbzone]

I based my design on the Hobbycnc design (didn't have the Igus book). If CNCzone had been around at the time, I would have done a few things different. I plan to upgrade several things. These WL1 bearing seem to do OK, but since you mention it, I might look into the other options.
Bill

[sol]

Originally posted by johntbyrne
I'd like to hear comments on linears and dust.

Here is how I keep a lot of the dust out of the works, it is surprisingly effective; the dust/chips are blown away before they have time to stick.

Hey, why is everybody laughing?

[strat]

another thought ....... i used pipe cleaners .... like the craft shops have ... wrapped around the rails next to the bushing over the top to other side and wrap around again did same for bottom rail keeps her clean and no hassels